ISO 15366-2:2014

Overview

ISO 15366-2:2014 - part of the ISO 15366 series on nuclear fuel technology - specifies a chemical separation and purification method for uranium and plutonium in nitric acid solutions prior to isotopic or isotope-dilution analysis (e.g., mass spectrometry or alpha spectrometry). This Part 2 procedure is tailored for extremely small analyte amounts (nanogram range and below), using solvent extraction chromatography on disposable mini-columns with TOPO-coated supports. The method is applicable to dissolved irradiated light water reactor (LWR) fuels and high active liquid waste from spent fuel reprocessing. Reported detection limits: 500 pg plutonium and 500 pg uranium.

Key technical topics and requirements

• Separation principle: Extraction chromatography using tri-n-octylphosphine-oxide (TOPO) coated on polyethylene or silica supports to retain Pu(IV) and U(VI) from 3 mol·L−1 HNO3.
• Valency control: Redox valency cycle (Fe(II) reduction, NaNO2 re-oxidation) to ensure plutonium is in the tetravalent state before loading.
• Elution strategy:
  • Plutonium eluted after reduction to Pu(III) (ascorbic acid/formic acid eluent).
  • Uranium eluted with ammonium carbamate and optionally purified further by anion exchange or fuming with 14 mol·L−1 HNO3.
• Mini-columns and support: Smaller disposable columns and specific support materials (polyethylene powder or silica gel) and column preparation procedures are detailed in the annex.
• Analytical performance: Flow-rate control for favourable kinetics (gravity flow ≤ 0.4 mL·min−1) and parallel blanks/controls to monitor cross-contamination and separation efficiency.
• Quality & safety: Use of suprapure reagents, laminar-flow clean conditions (shielded glove box or fume hood), and radioactive waste disposal of used columns.

Practical applications and users

• Radiochemistry and nuclear fuel laboratories performing isotopic analysis of uranium and plutonium at ultra-trace levels.
• Spent-fuel reprocessing plants analyzing dissolved samples and high active liquid waste.
• Safeguards and forensic laboratories requiring reliable chemical purification prior to mass spectrometry (ISO 8299) or alpha spectrometry (ISO 11483).
• Method supports ultra-trace isotopic dilution workflows and contamination-controlled sample prep for nuclear safeguards and material accountancy.

Related standards

• ISO 15366-1 (Part 1: procedures for larger sample amounts - same chemistry, different column/support)
• ISO 8299 (mass spectrometric isotopic analysis guidance)
• ISO 11483 (alpha spectrometry for plutonium/uranium)

Keywords: ISO 15366-2:2014, nuclear fuel technology, chemical separation, purification, uranium, plutonium, nitric acid, solvent extraction chromatography, TOPO, mini-column, isotopic analysis, mass spectrometry, nanogram range.